Pneumatic timer

ABSTRACT

An open-circuit pneumatic timer of the type comprising an air intake filter, a timing device having a throttling channel, a bellows and connecting openings, wherein the filter is housed in a regulator shaped like a circular cupel, the bottom of which rests directly on the throttling channel and is provided with an opening cooperating with the said channel. In this very simple and reliable timer, the distance covered by the fluid, outside the area where throttling is required, is kept to a minimum.

United States Patent [191 Faffart et al.

PNEUMATIC TIMER Knicii'bis ram"; Claude Paul Vinot, both of Nanterre,France Assignee i lea Telex neon itiilgNanterre,

7 France Filed: Feb. 2, 1972 Appl. No: 222,819

Foreign Application Priority Data Feb. 8, 1971 France 71.04132 U.S. Cl188/298, 200/34, 200/83 C Int. Cl F16f 9/04 Field of Search 188/270,301, 298; 200/34,

References Cited UNITED STATES PATENTS 12/1953 Schaefer 188/298 x 1 Mar.19, 1974 2,645,285 7/1953 Schaefer 188/298 X 2.8551481 10/1958 Lindahl188/298 X 3.178.524 4/1965 Frisk 188/298 X 3.213.333 10/1965 Mikina etal 188/298 X Primary Examiner-George E. A. Halvosa Attorney, Agent, orFirm-William Anthony Drucker [57] ABSTRACT An open-circuit pneumatictimer of the type comprising an air intake filter, a timing devicehaving a throttling channel, a bellows and connecting openings, whereinthe filter is housed in a regulator shaped like a circular cupel, thebottom of which rests directly on the throttling channel and is providedwith an opening cooperating with the said channel.

In this very simple and reliable timer, the distance covered by thefluid, outside the area where throttling is required, is kept to aminimum.

2 Claims, 2 Drawing Figures PATENTEDHARIQISM sis-L616 PNEUMATIC TIMERThis invention relates to a pneumatic timer whose components arespecially designed to be housed in a box fitted with auxiliary contactswhose operation it is to defer for a certain time, the said box beinggenerally designed to form part of a switching device such as acontact-maker, wherein several identical boxes are often mounted side byside. In some switching devices, timers are at present found wherein thefluid moves either in closed circuit or, conversely, in open circuit.

For example, in French Pat. No. 1,483,795 issued to the applicant, aircirculates in closed circuit, which means that the filter cannot bepositioned in the regulator; moreover, the bellows is separated from theregulator by the filter and by a considerable length of piping.

In [1.8. Pat. No. 3,213,333(MIKINA), circulation is in closed circuitand the device is such that it has been possible to omit the filter; onthe other hand, very careful sealing has been necessary, which has ledto a substantial increase in the size of the device.

A known timing device of the type in which the fluid circulates in opencircuit comprises, housed in a box, an air intake filter, a timingdevice equipped with a throttling channel whose effective length can beadjusted by means of a rotary regulator, a bellows expanding to amaximum volume under the action of an interior spring and channelsenabling the fluid to pass through all these components.

There is no need to recall all the advantages of opencircuit pneumatictimers, but on the other hand it is worth mentioning that in earlierdevices, the elements of change in their working, due to their veryprinciple, have not always been taken into account.

Thus, air intake filters whose surface did not take sufficient accountof short times have been in current use; moreover, the fluid was made tofollow such tortuous paths that long times were often impaired after afew weeks working. Moreover, it was often impossible to inspect orreplace the filter without partially dismantling the timing device.

As an example of previous devices, US. Pat. No. 2,662,594 (SCI-IAEFFER)can be quoted.

In this American patent, the filter is positioned under the regulator,which made the device quite substantially more complex; moreover, thevalve exhausting the air from the bellows is also positioned between theregulator and the bellows, which considerably decreases the effectivevolume of fluid and, consequently, narrows the range of setting times.

In French Pat. No. 1,153,769 (WESTINGHOUSE), the regulator carries nounit cooperating directly with the throttling circuits; moreover, thesuggested filter is awkward to make and involves precision manufactureif the rotation of the regulator is not to damage the filter.

The object of the invention is to provide a pneumatic timer in which theabove disadvantages are considerably reduced, by using a filter with thelargest possible surface, bearing in mind the small bulk made necessaryby the side-by-side mounting mentioned above, and in which measures havebeen taken for the distance covered by the fluid, outside the area wherethrottling is required, to be kept to a minimum. The penumatic timer inaccordance with the invention comprises, housed in a box, an air intakefilter, a timing device equipped with a throttling channel the effectinglength of which can be adjusted, a bellows expanding to maxiof whichhouses the filter and the bottom of which,-

resting directly on the throttling channel, comprises the said openingcooperating with the channel.

Other characteristics and advantages of the invention will emergeclearly below. In the attached drawings:

FIG. 1 is a sectional view of a timer in accordance with the invention,and

FIG. 2 is a view from below, with the bottom of the box removed. Thispneumatic timer consists mainly of box sides 1, a bottom 2 and apartition 3. The various component parts of the timer are assembledaround the partition 3. The timer is designed, in the non-limitingexample described, to cause the timed closing of contacts which havebeen shown in the form of a fixed contact 5 cooperating with a movingcontact 6 carried by a rocker arm. The latter consists of a leverpivoted at 9, one end 7 of which carries the moving contact 6, while theother end is divided into two parts 17 and 17 forming a fork (see FIG.2).

The bottom limb 17 of this fork carries an extension 16 equipped with apin 10 parallel to the axis of rotation of the pivot 9 (FIG. I).

The contact is closed by a spring 8 when this pin 10 has been releasedfrom a shoulder 1 l on the limb 12 of a bolt which pivots at 14.

This bolt has a second limb 13. This limb 13 is itself in the shape of afork (see FIG. 2) which bears on a cross-piece 15 connected to themovement of a bellows 21 by means of a return spring 18.

This cross-piece, shown in the at rest position in FIG. 1, can liftagainst a spring 20 when a thrust is exerted on a mobile plunger 19. Atit moves, the crosspiece 15 moves the pivotal unit 7, l7, l6 clockwise,which causes the contacts to open and the pin 10 to lock on the shoulder11. The timer proper comprises, besides the mobile plunger 19 and thespring 20, the aforementioned bellows 21, a front surface 22 of which isapplied by spring action from inside against the partition 3 by anannular shoulder 23 on a coaxial cylindrical rod 24. 1

This cylindrical rod goes through an opening 45 in the front face 22 andan opening 46 in the partition 3', it also goes through an opening 47 ina timing device 26 integral with a rubber washer 27 and through anopening 48 in the bottom 40 of a rotary regulator 25. FIG. 1 shows thatthe regulator 25 and the timing device 26 are applied directly to eachother and that the latter is applied against the partition 3 by means ofthe rubber washer 27, a spring component 39 and a washer 28, which isintegrated with the rod 24.

One can say that the rod 24 and its annular shoulder 23, together withthe washers 27 and 28 and the component 39, constitute a common springmeans of maintaining the parts 21, 26 and 25 against the partition 3.

Moreover, ports can be seen at 30, 31, 32, 33, 34 and 35 whichcommunicate with a throttling channel 36 formed in the surface of thetiming device 26. The

ports, whose section can be of a size suitable to prevent dust orcondensation from collecting, are moreover very short. The figure is notexactly to scale in order to make the drawing clearer, but it is easy tosee that the lengths of these various ports can be very short. This isdue to the relative positioning of the various components, which meansthat only the throttle of the throttling channel has to be taken intoaccount for long times, even when the section of the other ports isdecreased for some reason.

FIG. 1 shows a filter 29 whose diameter is very close to the width ofthe box. This filter is therefore large, and this has only been achieveddue to the fact that the filter is positioned inside the cupel-shapedregulator 25. In fact, as the main surfaces of the box of the timer areeither intended for purposes of mechanical or electrical connection orclose to other instruments, it is not desirable to position the filterthereon.

The filter 29 is, moreover, fixed axially by a cover 37, itself fixed onthe regulator 25 and, together with the latter, forming bent air intakes38. These ports act as baffle plates against foreign bodies, whileleaving a wide passing section for the fluid.

The working of the timer just described will now be explained withreference to FIG. 1. When the plunger 19 is pushed upwards, the aircontained in the bellows 21 escapes downward between the said bellowsand the said plunger. When the pressure on the plunger 19 ceases, thespring 20 applies the plunger 19 against the bottom of the bellows 21and thus creates suction which spreads through the ports 34, 35, 33, 32and 31, the throttling channel 36, the port 30, the filter 29 and thebent air intakes 38, into the open air.

The rotation of the regulator brings the port 30 into a positionopposite a certain portion of the channel 36 so that the distancecovered by the fluid before it reaches the port 31 can change and theworking time be altered.

Many modifications can be made, either to the shape of the variouscomponents or to their position, without departing from the concept ofthe invention.

Thus, the partition 3 could form part of a removable unit (indicated bya dotted line in FIG. 1), so that the timers could be mounted separatelyand be fitted in boxes on which the contacts had already been mounted.

What we claim is:

1. An open-circuit pneumatic timer comprising, housed in a box having awall, a bellows and spring means mounted inside said bellows foreffecting expansion of the inside volume of said bellows, a timing unitmounted outside the box in proximity to said wall and provided with athrottling channel, an opening in said wall for connecting the insidevolume of the bellows to the throttling channel, rotary means, mountedin contact with the timing unit, for adjusting the effective length ofthe throttling channel, said rotary means being in the form of acircular cupel having a bottom and an open part, an air filter mountedin the open part of said cupel, the bellows having frontal surfaceengaging said wall, the front surface of the bellows, said wall, thetiming unit and the bottom of the rotary means being provided withopenings, a rod member coaxial to the bellows mounted through saidopenings and having one end portion within the cupel, spring meansmounted about said end portion and engaging the bottom of the cupel forsecuring together the said cupel the timing unit and the bellows aboutsaid wall.

2. A timer as claimed in claim 1, further comprising a removable covermounted on the cupel and securing the filter, said cover being providedwith a plurality of bent air intakes.

1. An open-circuit pneumatic timer comprising, housed in a box having awall, a bellows and spring means mounted inside said bellows foreffecting expansion of the inside volume of said bellows, a timing unitmounted outside the box in proximity to said wall and provided with athrottling channel, an opening in said wall for connecting the insidevolume of the bellows to the throttling channel, rotary means, mountedin contact with the timing unit, for adjusting the effective length ofthe throttling channel, said rotary means being in the form of acircular cupel having a bottom and an open part, an air filter mountedin the open part of said cupel, the bellows having frontal surfaceengaging said wall, the front surface of the bellows, said wall, thetiming unit and the bottom of the rotary means being provided withopenings, a rod member coaxial to the bellows mounted through saidopenings and having one end portion within the cupel, spring meansmounted about said end portion and engaging the bottom of the cupel forsecuring together the said cupel the timing unit and the bellows aboutsaid wall.
 2. A timer as claimed in claim 1, further comprising aremovable cover mounted on the cupel and securing the filter, said coverbeing provided with a plurality of bent air intakes.